X-line routing for dense multi-chip-package interconnects

ABSTRACT

X-line routing arrangements for dense multi-chip-package interconnects are described. In an example, an electronic signal routing structure includes a substrate. A plurality of layers of conductive traces is disposed above the substrate. A first pair of ground traces is disposed in a first of the plurality of layers of conductive traces. A signal trace is disposed in a second of the plurality of layers of conductive traces, below the first layer. A second pair of ground traces is disposed in a third of the plurality of layers of conductive traces, below the first layer. The first and second pairs of ground traces and the signal trace provide an X-pattern routing from a cross-sectional perspective.

TECHNICAL FIELD

Embodiments of the invention are in the field of semiconductor packagesand, in particular, routing arrangements for dense multi-chip-packageinterconnects.

BACKGROUND

Today's consumer electronics market frequently demands complex functionsrequiring very intricate circuitry. Scaling to smaller and smallerfundamental building blocks, e.g. transistors, has enabled theincorporation of even more intricate circuitry on a single die with eachprogressive generation. Semiconductor packages are used for protectingan integrated circuit (IC) chip or die, and also to provide the die withan electrical interface to external circuitry. With the increasingdemand for smaller electronic devices, semiconductor packages aredesigned to be even more compact and must support larger circuitdensity. Furthermore, the demand for higher performance devices resultsin a need for an improved semiconductor package that enables a thinpackaging profile and low overall warpage compatible with subsequentassembly processing.

C4 solder ball connections have been used for many years to provide flipchip interconnections between semiconductor devices and substrates. Aflip chip or Controlled Collapse Chip Connection (C4) is a type ofmounting used for semiconductor devices, such as integrated circuit (IC)chips, MEMS or components, which utilizes solder bumps instead of wirebonds. The solder bumps are deposited on the C4 pads, located on the topside of the substrate package. In order to mount the semiconductordevice to the substrate, it is flipped over—the active side facing downon the mounting area. The solder bumps are used to connect thesemiconductor device directly to the substrate. However, this approachmay be limited by the size of the mounting area and may not readilyaccommodate stacked die.

On the other hand, conventional wire-bonding approaches may limit thenumber of semiconductor die that can reasonably be included in a singlesemiconductor package. Furthermore, general structural issues may arisewhen attempting to package a large number of semiconductor die in asemiconductor package.

Newer packaging and die-to-die interconnect approaches, such as throughsilicon via (TSV) and silicon interposer, are gaining much attentionfrom designers for the realization of high performance Multi-Chip Module(MCM) and System in Package (SiP). However, additional improvements areneeded in the evolution of semiconductor packages and die-to-dieinterconnection approaches.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a cross-sectional view of an exemplary routingstructure having an embedded interconnect bridge (EmIB) routing designwith 8 metal layers and including one microstrip and three striplinefeatures.

FIG. 2 is a plot providing an eye diagram comparison between amicrostrip feature and a stripline feature of an EmIB routing design.

FIG. 3A is a cross-sectional view of a microstrip building block.

FIG. 3B is a cross-sectional view of a stripline building block.

FIG. 3C is a cross-sectional view of a co-planar waveguide buildingblock.

FIG. 3D is a cross-sectional view a co-axial line building block.

FIG. 4A illustrates a cross-sectional view of a basic X-line routingbuilding block, in accordance with an embodiment of the presentinvention.

FIG. 4B illustrates a cross-sectional view of an exemplary X-line basedrouting structure having 8 metal layers, in accordance with anembodiment of the present invention.

FIG. 5A illustrates a cross-sectional view of a semiconductor packageincluding multiple die coupled with an embedded interconnect bridge(EmIB) having X-line routing therein, in accordance with an embodimentof the present invention.

FIG. 5B illustrates a cross-sectional view of a semiconductor packageincluding multiple die coupled with an embedded interconnect bridge(EmIB) having X-line routing therein, in accordance with an embodimentof the present invention.

FIG. 6 illustrates a cross-sectional view of a semiconductor packageincluding multiple die coupled with an interposer having X-line routingtherein, in accordance with an embodiment of the present invention.

FIG. 7 is a plot providing an eye diagram comparison between amicrostrip feature, a stripline feature, and an X-line feature routingdesign for present day design rules, in accordance with an embodiment ofthe present invention.

FIG. 8 is a schematic of a computer system, in accordance with anembodiment of the present invention.

DESCRIPTION OF THE EMBODIMENTS

Routing arrangements for dense multi-chip-package interconnects aredescribed. In the following description, numerous specific details areset forth, such as packaging and interconnect architectures, in order toprovide a thorough understanding of embodiments of the presentinvention. It will be apparent to one skilled in the art thatembodiments of the present invention may be practiced without thesespecific details. In other instances, well-known features, such asspecific semiconductor fabrication processes, are not described indetail in order to not unnecessarily obscure embodiments of the presentinvention. Furthermore, it is to be understood that the variousembodiments shown in the Figures are illustrative representations andare not necessarily drawn to scale.

One or more embodiments of the present invention are directed to X-linerouting for dense multi-chip-package interconnects. Embodimentsdescribed herein may have applications in high density interconnects,multi-chip-package, on-die interconnects, etc. In one embodiment,implementation of an X-line design effectively increases the distancebetween a signal line and surrounding ground traces to reduce thecapacitance. Such an approach may provide a structure having voids in aground layer directly above and underneath any signal line. As such,parallel plate capacitance may be minimized. In one embodiment,implementation of X-line routing is used to offset signals in adjacentlayers to avoid crosstalk across such layers. In a specific embodiment,metal density needs for manufacturability are met by the addition ofextra traces, which can be either grounded or floating.

To provide context, silicon interposer, silicon bridge, and embeddedinterconnect bridge (EmIB) technologies have been used to provide ultradense interconnections between dies in a package. Use of such featureshas capitalized on their capability to leverage fine silicon routingdesign rules. Depending on the overall packaging architecture and thecorresponding placement of input/output (I/O) bumps on packaged dies,the interconnect length can be 6 mm, or even longer. However,transmission lines on the silicon are highly lossy which may causesignal rising time to degrade quadratically with the routing length. Assuch, signaling over multi-millimeters for any of these technologies canbe challenging.

Addressing the above issues, microstrip or stripline designs have beenwidely implemented as routing options, an example of which is shown inFIG. 1 and described in greater detail below. In general, in order toachieve improved signaling performance, a cross section of the signaltrace tends to be larger for smaller resistance and the gap betweensignal and surround ground reference tends to be larger for smallercapacitance. Both requirements have led to a drive for thicker metal andvia layers. However, silicon processes are typically most compatiblewith structures having thin metal layers as well as and thin silicondioxide layers. Furthermore, with respect to present day silicon designrules, a stripline approach shows degraded signaling performance versusa microstrip approach, as shown in FIG. 2 and described in greaterdetail below.

FIG. 1 illustrates a cross-sectional view of an exemplary routingstructure having an embedded interconnect bridge (EmIB) routing designwith 8 metal layers and including one microstrip and three striplinefeatures. Referring to FIG. 1, a routing structure 100 includes aplurality of signal lines 102 of a first channel and a plurality ofsignal lines 104 of a second channel disposed above a substrate 101,such as a silicon substrate. A plurality of ground planes 106A, 106B,106C and 106D are disposed between the signal lines 102 and 104.Dielectric layers 108 and contact pads 110 are also included. In aspecific example, the ground planes may be meshed instead of solid inthe direction into the page (not shown). A microstrip 112 is formed fromground plane 106A and overlying signal lines 104. A first stripline 114is formed from ground planes 106A and 106B and sandwiched signal lines104. A second stripline 116 is formed from ground planes 106B and 106Cand sandwiched signal lines 102. A third stripline 118 is formed fromground planes 106C and 106D and sandwiched signal lines 102.

FIG. 2 is a plot 200 providing an eye diagram comparison between amicrostrip feature and a stripline feature of an EmIB routing design.Referring to plot 200, eye width (EW) as a function of distance (mm) isgreater the shorter the distance of the feature. For example, for a casehaving a target EW of 0.8 unit interval (UI), 0.13UI EW delta at 7 mm isobserved, which is significant. Since stripline routing encompasses amulti-layer design, such routing can provide a signaling bottleneck. Forexample, stripline routing often cannot meet the target EW requirementeven for 4 mm routing length in this particular example.

In order to provide a visual comparison for X-line routing ofembodiments of the present invention (described in association withFIGS. 4A and 4B below), FIGS. 3A-3D are cross-sectional views of basicbuilding blocks of various routing options. Referring to FIG. 3A, amicrostrip building block 300A includes a ground plane 302A below asignal line 304A. Referring to FIG. 3B, a stripline building block 300Bincludes a first ground plane 302B, a second ground plane 303B, and asandwiched signal line 304B. Referring to FIG. 3C, a co-planar waveguidebuilding block 300C includes a signal line 304C in between, and in thesame plane as, a first ground plane 302C and a second ground plane 303C.Referring to FIG. 3D, a co-axial line building block 300D includes asignal line 304D in between, and in the same plane as, a first groundplane 302D and a second ground plane 303D. Additionally, a third groundplane 305D and a fourth ground plane 306D sandwich signal line 304B inthe vertical direction.

Referring again to FIGS. 3A and 3B, microstrip and stripline routing arewidely used routing options. For example, trace routing for formingmulti-chip package (MCP) high speed input/output (HSIO) interconnectstructures is typically formed using microstrip and/or stripline tracerouting. As shown, microstrip routing may utilize a layer of signaltraces separated from a ground plane by a dielectric layer. Meanwhile,stripline routing may utilize a layer of signal traces sandwichedbetween two ground planes and separated from the ground planes bydielectric layers.

By contrast to the building blocks described in association with FIGS.3A-3D, an X-line routing design effectively increases the distancebetween a signal line and corresponding surrounding ground traces. Thearrangement may be used to effectively reduce the capacitance of therouting arrangement. As an example, FIG. 4A illustrates across-sectional view of a basic X-line routing building block, inaccordance with an embodiment of the present invention.

Referring to FIG. 4A, an X-line routing building block 400A includes acentral signal line 404. A first ground plane 402, second ground plane403, third ground plane 405 and fourth ground plane 406 are provided ina staggered arrangement, forming an X-shape with central signal line404. More specifically, ground planes 402 and 403 are co-planar in aplane above the central signal line 404, and ground planes 405 and 406are co-planar in a plane below the central signal line 404.Additionally, ground planes 402 and 405 are vertically aligned with oneanother, but do not overlap with or sandwich the central signal line404. Likewise, ground planes 403 and 406 are vertically aligned with oneanother, but do not overlap with or sandwich the central signal line404. The arrangement depicted in FIG. 4A thus effectively provides voids410 and 411 in ground layers directly above and underneath signal line404. As such, any parallel plate capacitance can be minimized. TheX-line arrangement offsets signals in adjacent layers to avoid crosstalkacross layers. In a specific embodiment, although not shown in FIG. 4A,requirements of metal density for manufacturability can be achieved bythe addition of extra traces, which can be either grounded or floating.

FIG. 4B illustrates a cross-sectional view of an exemplary X-line basedrouting structure having 8 metal layers, in accordance with anembodiment of the present invention. Referring to FIG. 4B, a routingstructure 400B includes a plurality of signal lines 452 of a firstchannel and a plurality of signal lines 454 of a second channel disposedabove a substrate 401, such as a silicon substrate. A plurality ofsegmented ground plane regions 456A, 456B, 456C and 456D, effectivelyincorporating voids along each segmented plane, are disposed between thesignal lines 452 and 454. Dielectric layers 458 are also included.Although not shown, contact pads may be further included above, or in atop portion of structure 400B. In a specific embodiment, additionalground or floating lines 460 may be included to increase the metaldensity in the signal layers, as depicted in FIG. 4B.

Structure 400B of FIG. 4B is an exemplary full design based on andX-line routing scheme. The structure may be contrasted with that ofFIG. 1. For example, in one embodiment, in order to reduce thecapacitance of the signal lines, ground traces (e.g., segments) areimplemented instead of a meshed plane. The ground traces and signallines of 400B are configured in an X pattern. In one embodiment, theX-line design maintains a suitable distance between the signal and thesurrounding ground traces to control an associated capacitance. Thestructure of FIG. 4B may be better understood as modifications to thedesign shown in FIG. 1. First, in one embodiment, structure 400Bincludes a half-pitch offset between signals across adjacent layers.Second, in one embodiment, structure 400B provides voids in the groundlayers above and underneath every signal trace to reduce the parallelplate capacitance. Due to the offset, signals across adjacent routinglayers do not couple directly. Thus, crosstalk across layers issuppressed. Finally, in one embodiment, the design of structure 400B hasadditional traces 460 between signal traces to increase the metaldensity suitable for a level compatible with silicon processing at aparticular technology node. The additional traces 460 do not affect thesignaling performance whether they are removed, grounded or leftfloating. In one embodiment, optimization can be achieved byappropriately sizing signal trace width and ground plane void width toachieve better signaling performance. Under such optimization, atrade-off may be struck between resistance, capacitance and crosstalkwithin structure 400B. Overall, in an embodiment, the X-line designeffectively reduces the capacitance, improves the resistance, andmaintains low crosstalk for silicon routing with multiple thin layers.

The structure 400B may be included in a semiconductor package or otherarrangement including one or more semiconductor die. The structure 400Bmay act as a routing component such as, but not limited to, a bridge, aninterposer, a package substrate, or a printed circuit board. In anycase, electrical pathways extend through the structure 400B. Substratebump-out regions may also be included, depending on the final form ofstructure 400B. The electrical pathways may connect to added componentsthrough solder bumps to define a routing structure similar to theembodiments described below, including a main routing region ofalternating signal traces and ground traces between such bump outregions. Other connections from the structure 400B may be made, forexample, for power connections to a power supply. The structure 400B mayoptionally include a variety of other layers such as, for example, corelayers, additional routing layers, and protective layers. The surface ofthe structure 400B may in certain embodiments be coupled to a structuresuch as a printed circuit board (PCB).

Referring again to FIG. 4B, as described above, structure 400B includesmultiple layers of signal traces and ground traces. In one embodiment,the ground traces and signal traces are adapted to be electricallycoupled to a component such as a semiconductor die structure fortransmitting signals to and from the component. FIG. 4B illustrates fourrouting layers extending in a horizontal direction, and includesalternating signal traces and ground traces. The traces may be formedfrom an electrically conductive material, for example, a metal includingcopper. A dielectric material may be positioned between the varioussignal traces and ground traces. As illustrated in the view of FIG. 4B,adjacent routing layers are configured so that there are verticallyalternating signal traces and ground traces.

Any suitable dielectric material may be positioned between the signaltraces and the ground traces. As illustrated in FIG. 4B, the dielectricmaterial includes dielectric material throughout most of the routinglayers of 400B and dielectric layer and in the uppermost layer and,possibly, on an underlying silicon substrate. In certain embodiments,the dielectric material between the signal traces and the ground tracesin the uppermost routing layer may be a material such as a photoresistmaterial that is used as a photoresist mask, with openings at padregions in a bump-out region (not shown in FIG. 4B). The lower routinglayers as illustrated in the embodiment of FIG. 4B include dielectricmaterial positioned between the traces and between the routing layers.Any suitable dielectric material may be used, including, for example,silicon dioxide, ceramic, glass, and polymeric materials. One specificexample of a suitable polymeric dielectric material is ABF (AjinomotoBuild-up Film), available from Ajinomoto Fine-Techno Company, Inc. Thedielectric structure may be varied from that illustrated in FIG. 4B, forexample, certain embodiments may have an uppermost dielectric layer thatis flush with an upper surface of the upper wiring layer, or may haveopen regions between the traces and bonding pads in the uppermost wiringlayer. Still other embodiments may, for example, use the same dielectricmaterial in all of the routing layers. The layers of dielectric andtraces may be formed using any suitable process, including, but notlimited to, a build-up layer lamination process. In an embodiment,substrate 401 is a silicon substrate. However, glass, organic or ceramicmay be used instead or as well. In an embodiment using an EmIBarchitecture, a piece of silicon is embedded into an organic package,such that the materials are more like silicon dioxide instead of packagematerial.

While four routing layers are illustrated in FIG. 4B, embodiments mayinclude more or less rows of alternating signal and ground traces. Anysuitable number of traces per layer may also be used, with differentlayers having a different number of traces if desired. Embodiments mayalso include additional layers above and/or below the routing layers.For example, an additional layer may be formed from one or moresub-layers including, but not limited to, one or more additional routinglayers (including metal and dielectric), protective layers, core layers,metallization layers, and other device layers (for example, capacitorlayers). The routing structure 400B may be formed as a discretecomponent or as a portion of another component. The routing structure400B may be formed as part of an active component or as part or all of apassive component.

In an example implementation, FIG. 5A illustrates a cross-sectional viewof a semiconductor package 500A including multiple die coupled with anEmIB having X-line routing therein, in accordance with an embodiment ofthe present invention. Referring to FIG. 5A, the semiconductor package500A includes a first die 502 (such as a CPU, memory chipset, etc.) anda second die 504 (such as a CPU, memory chipset, etc.). The first die502 and second die 504 are coupled to an EmIB 506 through bumps 508 and510 of the first die 502 and second die 504, respectively, and bond pads512 of the silicon bridge, e.g., by thermal compression bonding (TCB).The first die 502, second die 504, and EmIB 506 are included withadditional routing layers 514, as depicted in FIG. 5A. The additionalrouting layers may be simple or complex and may be for coupling to otherpackages or may form part or all of an organic package or printedcircuit board (PCB), etc. In one embodiment, the routing of EmIB 506 hasan X-line routing such as described in association with FIG. 4A, asparticular embodiment of which is described in association with FIG. 4B.In another embodiment, a silicon bridge is used and is not embedded inthe package, but rather in an open cavity.

In another example implementation, FIG. 5B illustrates a cross-sectionalview of a semiconductor package 500B including multiple die coupled withan embedded interconnect bridge (EmIB) having X-line routing therein, inaccordance with an embodiment of the present invention. Referring toFIG. 5B, the semiconductor package 500B includes a first die 552 (suchas a central processing unit, CPU) and a second die 554 (such as anadditional CPU or a memory die or memory die stack, the memory die stackdepicted in FIG. 5B). The first die 552 and second die 554 are coupledto an EmIB 556 through bumps 558 and 560 of the first die 552 and seconddie 554, respectively, e.g., by thermal compression bonding (TCB). TheEmIB 556 is embedded in substrate (e.g., flexible organic substrate) orboard (such as epoxy PCB material) material 570, as depicted in FIG. 5B.In one embodiment, the routing of EmIB 556 has an X-line routing such asdescribed in association with FIG. 4A, as particular embodiment of whichis described in association with FIG. 4B.

In an exemplary implementation, FIG. 6 illustrates a cross-sectionalview of a semiconductor package 600 including multiple die coupled withan interposer having X-line routing therein, in accordance with anembodiment of the present invention. Referring to FIG. 6, thesemiconductor package 600 includes a first die 602 and a second die 604.The first die 602 and second die 604 are coupled to an interposer 606,such as a silicon interposer. The first die 602 and second die 604 arecoupled to the interposer 606 through bumps 608 and 610 of the first die602 and second die 604, respectively, and bond pads 612 of theinterposer 606, e.g., by thermal compression bonding (TCB). Theinterposer 606 couples the first die 602 and second die 604 with anorganic package 620. The organic package 620 may include its own routinglayers, as depicted in FIG. 6. Coupling through interposer 606 may beachieved by use of through silicon vias (TSVs) 630, as is also depictedin FIG. 6. In one embodiment, the routing of interposer 606 has anX-line routing such as described in association with FIG. 4A, aparticular embodiment of which is described in association with FIG. 4B.

The examples shown in FIGS. 5A, 5B and 6 may provide designs forachieving high bandwidth dense interconnects between dies. The X-linedesigns used therein (e.g., in the form of a silicon bridge, aninterposer, or an embedded interconnect bridge) may provide a signalingadvantage over previous routing approaches. For example, FIG. 7 is aplot 700 providing an eye diagram comparison between a microstripfeature, a stripline feature, and an X-line feature routing design forpresent day design rules, in accordance with an embodiment of thepresent invention. Referring to plot 700, EW is shown as a function ofdistance (mm) for a metal layer set at 1.3 μm thickness, a via layer setat 0.7 μm thickness, and a routing pitch set at 14 μm. The eye width at1.6 GT/s shows that X-line routing is significantly improved overstripline and microstrip routing at the same routing density. As such,in an embodiment, an X-line design can be implemented to remove thebottleneck associated with stripline routing. Furthermore, the X-linerouting design may be used for providing electrical improvements inmulti-layer silicon interconnect designs.

Thus, one or more embodiments described herein relate to substraterouting structures in which reduced crosstalk is achieved whileutilizing a minimum number of layers, without any increase in thesurface area of the substrate or die. Certain embodiments includesegmenting ground traces within a same horizontal layer. Embodiments mayalso include alternating signal and ground traces in the verticaldirection. Implementations include applications in multi-chip packages,organic package substrates, transmission lines, 2.5 D (Si featurebetween die and board), on-die, on package, etc. architectures. Suchimplementations may enable increased density for IOs to provideincreased signals at low speed, which may be more efficient than fewersignals at high speed.

FIG. 8 is a schematic of a computer system 800, in accordance with anembodiment of the present invention. The computer system 800 (alsoreferred to as the electronic system 800) as depicted can embody anX-line routing arrangement for dense multi-chip-package interconnectsaccording to any of the several disclosed embodiments and theirequivalents as set forth in this disclosure. The computer system 800 maybe a mobile device such as a netbook computer. The computer system 800may be a mobile device such as a wireless smart phone. The computersystem 800 may be a desktop computer. The computer system 800 may be ahand-held reader. The computer system 800 may be a server system. Thecomputer system 800 may be a supercomputer or high-performance computingsystem.

In an embodiment, the electronic system 800 is a computer system thatincludes a system bus 820 to electrically couple the various componentsof the electronic system 800. The system bus 820 is a single bus or anycombination of busses according to various embodiments. The electronicsystem 800 includes a voltage source 830 that provides power to theintegrated circuit 810. In some embodiments, the voltage source 830supplies current to the integrated circuit 810 through the system bus820.

The integrated circuit 810 is electrically coupled to the system bus 820and includes any circuit, or combination of circuits according to anembodiment. In an embodiment, the integrated circuit 810 includes aprocessor 812 that can be of any type. As used herein, the processor 812may mean any type of circuit such as, but not limited to, amicroprocessor, a microcontroller, a graphics processor, a digitalsignal processor, or another processor. In an embodiment, the processor812 includes, or is coupled with, an X-line routing arrangement fordense multi-chip-package interconnects, as disclosed herein. In anembodiment, SRAM embodiments are found in memory caches of theprocessor. Other types of circuits that can be included in theintegrated circuit 810 are a custom circuit or an application-specificintegrated circuit (ASIC), such as a communications circuit 814 for usein wireless devices such as cellular telephones, smart phones, pagers,portable computers, two-way radios, and similar electronic systems, or acommunications circuit for servers. In an embodiment, the integratedcircuit 810 includes on-die memory 816 such as static random-accessmemory (SRAM). In an embodiment, the integrated circuit 810 includesembedded on-die memory 816 such as embedded dynamic random-access memory(eDRAM).

In an embodiment, the integrated circuit 810 is complemented with asubsequent integrated circuit 811. Useful embodiments include a dualprocessor 813 and a dual communications circuit 815 and dual on-diememory 817 such as SRAM. In an embodiment, the dual integrated circuit810 includes embedded on-die memory 817 such as eDRAM.

In an embodiment, the electronic system 800 also includes an externalmemory 840 that in turn may include one or more memory elements suitableto the particular application, such as a main memory 842 in the form ofRAM, one or more hard drives 844, and/or one or more drives that handleremovable media 846, such as diskettes, compact disks (CDs), digitalvariable disks (DVDs), flash memory drives, and other removable mediaknown in the art. The external memory 840 may also be embedded memory848 such as the first die in a die stack, according to an embodiment.

In an embodiment, the electronic system 800 also includes a displaydevice 850, an audio output 860. In an embodiment, the electronic system800 includes an input device such as a controller 870 that may be akeyboard, mouse, trackball, game controller, microphone,voice-recognition device, or any other input device that inputsinformation into the electronic system 800. In an embodiment, an inputdevice 870 is a camera. In an embodiment, an input device 870 is adigital sound recorder. In an embodiment, an input device 870 is acamera and a digital sound recorder.

As shown herein, the integrated circuit 810 can be implemented in anumber of different embodiments, including an X-line routing arrangementfor dense multi-chip-package interconnects according to any of theseveral disclosed embodiments and their equivalents, an electronicsystem, a computer system, one or more methods of fabricating anintegrated circuit, and one or more methods of fabricating an electronicassembly that includes an X-line routing arrangement for densemulti-chip-package interconnects according to any of the severaldisclosed embodiments as set forth herein in the various embodiments andtheir art-recognized equivalents. The elements, materials, geometries,dimensions, and sequence of operations can all be varied to suitparticular I/O coupling requirements including array contact count,array contact configuration for a microelectronic die embedded in aprocessor mounting substrate according to any of the several disclosedX-line routing arrangement for dense multi-chip-package interconnectsembodiments and their equivalents. A foundation substrate may beincluded, as represented by the dashed line of FIG. 8. Passive devicesmay also be included, as is also depicted in FIG. 8.

Embodiments of the present invention include X-line routing arrangementsfor dense multi-chip-package interconnects.

In an embodiment, an electronic signal routing structure includes asubstrate. A plurality of layers of conductive traces is disposed abovethe substrate. A first pair of ground traces is disposed in a first ofthe plurality of layers of conductive traces. A signal trace is disposedin a second of the plurality of layers of conductive traces, below thefirst layer. A second pair of ground traces is disposed in a third ofthe plurality of layers of conductive traces, below the first layer. Thefirst and second pairs of ground traces and the signal trace provide anX-pattern routing from a cross-sectional perspective.

In one embodiment, the first pair of ground traces is a first pair ofco-planar ground traces, and the second pair of ground traces is asecond pair of co-planar ground traces.

In one embodiment, the first pair of co-planar ground traces isvertically aligned with the second pair of co-planar ground traces.

In one embodiment, from a vertical perspective, the traces of the firstand second pairs of co-planar ground traces do not overlap with thesignal trace.

In one embodiment, the plurality of layers of conductive traces isdisposed in one or more dielectric layers disposed above the substrate.

In one embodiment, the substrate is a bulk crystalline siliconsubstrate, and the plurality of layers of conductive traces is composedof copper traces.

In one embodiment, the electronic signal routing structure furtherincludes additional signal traces and ground traces providing additionalX-pattern routing.

In one embodiment, a half-pitch offset is provided horizontally betweensignal traces across adjacent layers of conductive traces having signaltraces therein.

In an embodiment, a semiconductor package includes first and secondadjacent semiconductor dies. A silicon bridge structure electricallycouples the first and second semiconductor dies, and includes aplurality of layers of conductive traces disposed above a substrate, afirst pair of ground traces disposed in a first of the plurality oflayers of conductive traces, a signal trace disposed in a second of theplurality of layers of conductive traces, below the first layer, and asecond pair of ground traces disposed in a third of the plurality oflayers of conductive traces, below the first layer. The first and secondpairs of ground traces and the signal trace provide an X-pattern routingfrom a cross-sectional perspective. A plurality of package routinglayers is also included. The silicon bridge structure is disposed in oneof the package routing layers, the first and second die are disposed onthe plurality of package routing layers, and at least one of the firstand second die is electrically coupled to the plurality of packagerouting layers.

In one embodiment, the first pair of ground traces is a first pair ofco-planar ground traces, and the second pair of ground traces is asecond pair of co-planar ground traces.

In one embodiment, the first pair of co-planar ground traces isvertically aligned with the second pair of co-planar ground traces.

In one embodiment, from a vertical perspective, the traces of the firstand second pairs of co-planar ground traces do not overlap with thesignal trace.

In one embodiment, the plurality of layers of conductive traces isdisposed in one or more dielectric layers disposed above the substrateof the silicon bridge structure.

In one embodiment, the substrate of the silicon bridge structure is abulk crystalline silicon substrate, and the plurality of layers ofconductive traces is composed of copper traces.

In one embodiment, the silicon bridge structure further includesadditional signal traces and ground traces providing additionalX-pattern routing, and a half-pitch offset is provided horizontallybetween signal traces across adjacent layers of conductive traces havingsignal traces therein.

In an embodiment, a semiconductor package includes first and secondadjacent semiconductor dies. An embedded interconnect bridge (EmIB)structure electrically couples the first and second semiconductor dies,and includes a plurality of layers of conductive traces disposed above asubstrate, a first pair of ground traces disposed in a first of theplurality of layers of conductive traces, a signal trace disposed in asecond of the plurality of layers of conductive traces, below the firstlayer, and a second pair of ground traces disposed in a third of theplurality of layers of conductive traces, below the first layer. Thefirst and second pairs of ground traces and the signal trace provide anX-pattern routing from a cross-sectional perspective. A flexible organicsubstrate or epoxy board is also included. The EmIB structure isdisposed in the flexible organic substrate or epoxy board, and the firstand second semiconductor dies are disposed on the flexible organicsubstrate or epoxy board.

In one embodiment, the first pair of ground traces is a first pair ofco-planar ground traces, and the second pair of ground traces is asecond pair of co-planar ground traces.

In one embodiment, the first pair of co-planar ground traces isvertically aligned with the second pair of co-planar ground traces.

In one embodiment, from a vertical perspective, the traces of the firstand second pairs of co-planar ground traces do not overlap with thesignal trace.

In one embodiment, the plurality of layers of conductive traces isdisposed in one or more dielectric layers disposed above the substrateof the EmIB structure.

In one embodiment, the substrate of the EmIB structure is a bulkcrystalline silicon substrate, and the plurality of layers of conductivetraces is composed of copper traces.

In one embodiment, the EmIB structure further includes additional signaltraces and ground traces providing additional X-pattern routing, and ahalf-pitch offset is provided horizontally between signal traces acrossadjacent layers of conductive traces having signal traces therein.

In one embodiment, a semiconductor package includes first and secondadjacent semiconductor dies. A silicon interposer structure is disposedbelow and electrically couples the first and second semiconductor dies.The silicon interposer structure includes a plurality of layers ofconductive traces disposed above a substrate, a first pair of groundtraces disposed in a first of the plurality of layers of conductivetraces, a signal trace disposed in a second of the plurality of layersof conductive traces, below the first layer, and a second pair of groundtraces disposed in a third of the plurality of layers of conductivetraces, below the first layer. The first and second pairs of groundtraces and the signal trace provide an X-pattern routing from across-sectional perspective. An organic package substrate is alsoincluded and is disposed below and is electrically coupled to thesilicon interposer structure. The organic package substrate includes aplurality of routing layers therein.

In one embodiment, the first pair of ground traces is a first pair ofco-planar ground traces, and the second pair of ground traces is asecond pair of co-planar ground traces.

In one embodiment, the first pair of co-planar ground traces isvertically aligned with the second pair of co-planar ground traces.

In one embodiment, from a vertical perspective, the traces of the firstand second pairs of co-planar ground traces do not overlap with thesignal trace.

In one embodiment, the plurality of layers of conductive traces isdisposed in one or more dielectric layers disposed above the substrateof the silicon interposer structure.

In one embodiment, the substrate of the silicon interposer structure isa bulk crystalline silicon substrate, and the plurality of layers ofconductive traces is composed of copper traces.

In one embodiment, the silicon interposer structure further includesadditional signal traces and ground traces providing additionalX-pattern routing, and a half-pitch offset is provided horizontallybetween signal traces across adjacent layers of conductive traces havingsignal traces therein.

In one embodiment, the organic package substrate is electrically coupledto the silicon interposer structure by one or more through-silicon-vias(TSVs) disposed in the silicon interposer structure.

What is claimed is:
 1. A semiconductor package, comprising: first andsecond adjacent semiconductor dies; a silicon bridge structureelectrically coupling the first and second semiconductor dies, andcomprising a plurality of layers of conductive traces disposed above asubstrate of the silicon bridge structure, a first pair of ground tracesdisposed in a first of the plurality of layers of conductive traces, asignal trace disposed in a second of the plurality of layers ofconductive traces, below the first layer, and a second pair of groundtraces disposed in a third of the plurality of layers of conductivetraces, below the first layer and the second layer, wherein the firstand second pairs of ground traces and the signal trace provide anX-pattern routing from a cross-sectional perspective; and a plurality ofpackage routing layers, wherein the silicon bridge structure is disposedin one of the package routing layers, the first and second die aredisposed on the plurality of package routing layers, and at least one ofthe first and second die is electrically coupled to the plurality ofpackage routing layers.
 2. The semiconductor package of claim 1, whereinthe first pair of ground traces is a first pair of co-planar groundtraces, and the second pair of ground traces is a second pair ofco-planar ground traces.
 3. The semiconductor package of claim 2,wherein the first pair of co-planar ground traces is vertically alignedwith the second pair of co-planar ground traces.
 4. The semiconductorpackage of claim 3, wherein, from a vertical perspective, the traces ofthe first and second pairs of co-planar ground traces do not overlapwith the signal trace.
 5. The semiconductor package of claim 1, whereinthe plurality of layers of conductive traces is disposed in one or moredielectric layers disposed above the substrate of the silicon bridgestructure.
 6. The semiconductor package of claim 1, wherein thesubstrate of the silicon bridge structure is a bulk crystalline siliconsubstrate, and the plurality of layers of conductive traces comprisescopper traces.
 7. The semiconductor package of claim 1, the siliconbridge structure further comprising: additional signal traces and groundtraces providing additional X-pattern routing, wherein a half-pitchoffset is provided horizontally between signal traces across adjacentlayers of conductive traces having signal traces therein.
 8. Asemiconductor package, comprising: first and second adjacentsemiconductor dies; an embedded interconnect bridge (EmIB) structureelectrically coupling the first and second semiconductor dies, andcomprising a plurality of layers of conductive traces disposed above asubstrate of the EmIB structure, a first pair of ground traces disposedin a first of the plurality of layers of conductive traces, a signaltrace disposed in a second of the plurality of layers of conductivetraces, below the first layer, and a second pair of ground tracesdisposed in a third of the plurality of layers of conductive traces,below the first layer and the second layer, wherein the first and secondpairs of ground traces and the signal trace provide an X-pattern routingfrom a cross-sectional perspective; and a flexible organic substrate orepoxy board, wherein the EmIB structure is disposed in the flexibleorganic substrate or epoxy board, and the first and second semiconductordies are disposed on the flexible organic substrate or epoxy board. 9.The semiconductor package of claim 8, wherein the first pair of groundtraces is a first pair of co-planar ground traces, and the second pairof ground traces is a second pair of co-planar ground traces.
 10. Thesemiconductor package of claim 9, wherein the first pair of co-planarground traces is vertically aligned with the second pair of co-planarground traces.
 11. The semiconductor package of claim 10, wherein, froma vertical perspective, the traces of the first and second pairs ofco-planar ground traces do not overlap with the signal trace.
 12. Thesemiconductor package of claim 8, wherein the plurality of layers ofconductive traces is disposed in one or more dielectric layers disposedabove the substrate of the EmIB structure.
 13. The semiconductor packageof claim 8, wherein the substrate of the EmIB structure is a bulkcrystalline silicon substrate, and the plurality of layers of conductivetraces comprises copper traces.
 14. The semiconductor package of claim8, the EmIB structure further comprising: additional signal traces andground traces providing additional X-pattern routing, wherein ahalf-pitch offset is provided horizontally between signal traces acrossadjacent layers of conductive traces having signal traces therein.